Mixer and mixing unit for mixing a paste

ABSTRACT

A mixer and a mixing unit for mixing and handling industrial side-stream materials. The mixer ( 6 ) is arranged onto a movable work machine ( 5 ) and it is used for mixing at least two side-stream materials to form a geopolymer. The mixer ( 6 ) comprises: a bucket part ( 27 ) for loading and transferring the side-stream material; a mixer apparatus ( 26 ) for mixing the side-stream material which has been loaded into the space delimited by the bucket part ( 27 ); a connecting device ( 25 ) for connecting the mixer ( 6 ) to a boom of a work machine ( 5 ); and at least one measuring device (S 1 , S 2 , S 3 ) for determining properties of the material in the mixer ( 6 ).

BACKGROUND OF THE INVENTION

The invention relates to a new mixer for use in the mixing of industrialside-stream materials when manufacturing a geopolymer.

Further, the invention relates to a mixer unit for mixing and handlingside-stream materials.

The object of the invention is described in more detail in the preamblesof independent claims of the application.

Large quantities of industrial side-stream materials, such as ashes,slags and precipitates, are formed in industry. Often, it is difficultto utilize these materials due to the components contained in them. Inaddition, handling of these side-stream materials has been found to bedifficult. In consequence, side-stream materials are difficult toutilize and they even have to be tipped in waste piles. Productionplants incur significant costs and environmental risks because of waste.

BRIEF DESCRIPTION OF THE INVENTION

The idea of the invention is to provide a new and improved mixer andmixing unit for mixing and handling industrial side-stream materials.

Characteristic features of the mixer according to the invention arepresented in the characterizing part of the first independent deviceclaim.

Characteristic features of the mixer unit according to the invention arepresented in the characterizing part of the second independent deviceclaim.

The idea of the proposed solution is that at least one industrialside-stream material is mixed by means of a mixer connected to a movablework machine. The solution thereby utilizes a movable mixer.

One advantage of the proposed solution is that a mixer unit formed by awork machine and a mixer is a small investment and functionally veryflexible. It is easy to scale the solution by increasing the number ofthe units. In addition, the solution is very simple and does not requiremassive equipment. It is not necessary to build any new fixedinfrastructure at a factory waste disposal site or a corresponding worksite due to the proposed solution.

Further, an advantage of the proposed new method is that difficultlyhandleable side-stream materials may be processed at a factory wastedisposal site to a form in which their transporting by normaltransportation means to a site of usage is efficient and safe. In themethod, paste may be worked in the mixer into a ready-to-cast pastebatch in one operation.

The proposed solution is suited for manufacture and handling on anindustrial scale and the end product may be an industrial product.Geopolymers may be manufactured from industrial side-streams by means ofthe solution in the same pace as the side-streams are being produced.

It is to note that in this application a geopolymer may also mean analkali-activated material. In light of the current knowledge ageopolymer and an alkali-activated material mean the same material. Inthis type of material, silicon oxide SiO₂ and aluminium oxide Al₂O₃ havereacted and formed a compression-resistant solid structure. Sometimesgeopolymers are also referred to in literature as a subset ofalkali-activated materials. In this type of material, silicon oxide SiO₂and aluminium oxide Al₂O₃ are instrumental in the formation of so-calledgeopolymer cement which is a cement-like binder. Geopolymer cement maybe utilized in the manufacture of a compression-resistant, concrete-likematerial.

Further, it may be stated that a geopolymer is a cementitious binderwhich may be utilized for the manufacture of a concrete-like material,and which is produced from a silicon and aluminium containing material,for example a side-stream material in alkaline, i.e. high pH,conditions. A concrete-like strong material produced in a reaction ofindustrial mineral side-streams and alkaline components is alsogenerally called a geopolymer. Alkaline components such as sodium-basedsolutions are used as reactive agents in the manufacture.

The idea of one embodiment is that the mixer is designed and intendedfor the mixing of industrial side-stream materials in the manufacture ofa geopolymer. The mixer comprises a bucket part for loading andtransferring the side-stream material. The bucket part thus forms aspace into which admixtures may be loaded and fed. Further, the mixercomprises a mixer apparatus for mixing the side-stream material whichhas been loaded into the space delimited by the bucket. The mixer may beconnected to a suitable work machine by means of a connecting device.Typically the work machine has a boom to which the mixer may beconnected such that it may be moved in multiple ways by means ofarticulations and actuators of the boom. The connecting device enablesthe mixer to be removed, whereby the work machine may at times be usedfor other work tasks, for example as proposed in this application forloading a geopolymer quarry material to a crusher as well as for loadingcrushed material. The mixer may also be removed for the time ofmaintenance and repair.

The idea of one embodiment is that the above-mentioned mixer is pushableor forcible by means of the work machine into a pile formed by tippedmaterial for loading the material to be handled into the mixer. Thus, noseparate loading equipment is needed and the operation is efficient.Further, the configuration is advantageous when the side-stream materialis in a particularly difficulty handleable form.

The idea of one embodiment is that the mixer is a bucket-type device inwhich the volume of the bucket part is at least 1 m³. The volume of themixer may be 5-7 m³ or even more.

The idea of one embodiment is that the bucket part of the mixer is anopen-top structure, whereby the mixer is arranged to receive materialfrom an upper feed or admixture station. Thus the mixer may simply beintroduced under a hopper, a dispenser or a feeder. Admixing may therebybe quick and efficient when it is done directly into the mixer withoutintermediate steps and additional equipment.

The idea of one embodiment is that the mixer is tiltable from a mixingposition to an unloading position, in which unloading position the pastelocated in the mixer is arranged to flow out of the bucket part by theeffect of gravity. The side-stream materials may, with each other aswell as possible admixtures and water, form a dough-like or viscouspaste, the unloading of which without tipping is difficult.

The idea of one embodiment is that the mixer has a horizontal mixingposition and it is tiltable downwards relative to the mixing position.The unloading position may be some predetermined downwardly slopingangular position. The mixer may be tilted such that its bottom part isarranged in a vertical direction, and further, the mixer may in somecases be even tilted over the vertical tilting position, i.e. close toupside down. Thereby the unloading of difficulty handleable dough-likepastes may be facilitated. It is also possible to swing or oscillate themixer during mixing in order to facilitate the mixing.

The idea of one embodiment is that between the mixer and a free end ofthe boom of the work machine there is a tilting device for tilting themixer to the unloading position.

The idea of one embodiment is that the mixer is tiltable to theunloading position by means of articulation of the boom of the workmachine.

The idea of one embodiment is that the mixer comprises a tilting deviceby which the bucket part is tiltable in relation to a pivot joint fromthe mixing position to the unloading position.

The idea of one embodiment is that the mixer apparatus of the mixer isoperatable during unloading. This may significantly facilitate the pasteformed by difficultly handleable side-stream materials. For example, apaste comprising mainly green liquor precipitate may be a viscous ordough-like material, the unloading of which just by dumping or tippingmay be difficult or even impossible.

The idea of one embodiment is that the mixer comprises at least onevibrator device for facilitating the unloading of the bucket part.

The idea of one embodiment is that the mixer comprises at least onevibrator device which is operatable not only during unloading but alsoduring mixing in order to facilitate the mixing.

The idea of one embodiment is that said vibrator device comprises arotary eccentric body. Alternatively the vibrator device may comprise animpact device.

The idea of one embodiment is that the mixer comprises at least onemeasuring device for determining properties of the material in themixer. Measurement data from a measuring unit may be transmitted bymeans of a wireless data communication connection to the admixturestation, whereby the system may in advance calculate the amount ofnecessary admixtures relative to the obtained measurement data. Thesystem may also in advance prepare admixture batches in such a way thatthe operation at the admixture station is as smooth and as efficient aspossible.

The idea of one embodiment is that the mixer comprises at least oneweighing device for determining a mass of the material loaded into thebucket part. Alternatively the weighing device may be provided inconnection with the work machine, for example onto the boom or axles.Thereby real-time data are obtained on the weight of the handledmaterial and paste.

The idea of one embodiment is that the mixer comprises at least onemeasuring device for determining moisture of the material in the mixer.On the basis of moisture data, additional moistening at the admixturestation may be adjusted as necessary, and further the moisture data maybe used for adjusting the amount of other admixtures.

The idea of one embodiment is that the mixer comprises at least onemeasuring device for determining the force required for mixing.Properties of the paste being mixed, such as structure, plasticity,moisture and homogeneity, may be determined from the force resisting themixing.

The idea of one embodiment is that the mixer comprises at least onecamera for visually inspecting the composition of the paste. Visual datafrom the camera may be transmitted to an operator of the work machine oran operator working at a monitoring station or an expert.

The idea of one embodiment is that the mixer comprises at least onehorizontal mixer shaft which is rotatable by means of a rotation motorabout its longitudinal axis. The mixer shaft is provided with aplurality of mixer blades having mixing surfaces in an angular positionrelative to the longitudinal direction of the mixer shaft.

The idea of one embodiment is that the rotation motor for rotating themixer shaft is a hydraulic motor. In the booms of work machines,hydraulic energy is typically well available. Further, the rotationmotor and power transmission may be arranged outside the bucket part,separately from the materials being mixed.

The idea of one embodiment is that the mixer comprises two horizontalmixer shafts which are rotatable by means of at least one rotation motorabout their longitudinal axes. The rotating directions of the mixershafts are opposite to each other and each one of the mixer shafts isprovided with a plurality of mixer blades having mixing surfaces in anangular position relative to the longitudinal direction of the mixershaft. The mixer blades of the adjacent mixer shafts are provided ataxially different locations relative to each other, such that the mixerblades of the adjacent mixer shafts are partly overlapped. This type ofdouble-shaft mixer has been found to be particularly efficient in themixing of side-stream materials.

The idea of one embodiment is that the upper surface of the bottom ofthe bucket part of the mixer is shaped to correspond to theabove-mentioned one or two mixer shafts with mixer elements. Thus thebottom may comprise one or two arched bottom parts at the mixer shafts.The shape of the bottom may also affect the efficiency of mixing to somedegree.

The idea of one embodiment is that the mixer unit comprises a movablework machine and a mixer connected to a boom thereof. The work machinemay be a wheel loader. As the mixer is connected to the work machine, itis functionally a very flexible movable unit. If necessary, two or moreunits may operate at a factory waste disposal site or a correspondingwork site, so the system is easily scalable.

The idea of one embodiment is that the mixer is connected to anexcavator, a forklift, a telescopic handler, a tractor or anotherindependently movable and controllable work machine or vehiclecomprising a movable chassis.

The idea of one embodiment is that the mixer unit is an independentlycontrollable mobile device. In some cases, control of the mixer unit maybe provided by means of manned remote control. Further, the operation ofmixer units operating in a work area may be automatized, whereby theymay even operate in an unmanned mode.

The idea of one embodiment is that the mixing of fed materials andsubstances is carried out mainly during transfer of the mixer. In otherwords, the mixing is carried out during transfer from the admixturestation to an unloading site, and thus there is no need for stationarymixing.

The idea of one embodiment is that the solution relates to anarrangement at a factory waste disposal site. The arrangement comprisesat least one waste pile of a first industrial side-stream material. Thisfirst side-stream material may be the main component of the mixturebeing formed. The arrangement further comprises at least one movablework machine which is provided with a mixer. The work machine isarranged to take said first industrial side-stream material directlywith the mixer from said waste pile for handling it by the mixer. Thus,no separate device is needed for loading. The arrangement also comprisesan admixture station having at least a first feed device for feeding asecond industrial side-stream material into the material in the mixer ofthe work machine. The mixer device mixes said side-stream materials,whereby a geopolymeric hardenable paste is formed, which is unloadedafter mixing onto a casting area where said side-stream materialscontinue reacting, and the material produced begins to harden. Hardeningis allowed to continue at least to a partial hardness at which thematerial has a strength which is suitable for crushing. The unloadingmay be described by way of casting of the dough-like paste, such that adesired formation may be formed from the paste. In the proposedarrangement the material being handled is kept in the mixer of the workmachine for the time of the whole handling process from the waste pileup to the casting area. The proposed arrangement is logisticallyefficient and requires only minor investments.

The idea of one embodiment is that the arrangement is free of transferdevices other than said work machine between the waste pile and thecasting area.

The idea of one embodiment is that the work machine provided with themixer is a multi-functional device which is arranged to operate as aloading, transferring, mixing and casting device between the waste pileand the casting area.

The idea of one embodiment is that the mixing unit, admixture stationand crushing device as described in this document may all be movabledevices which may be easily transferred even to different worksites andfactory waste disposal sites. It is for example possible that a chain ofmachines formed by said devices may circulate different worksites underoperation by a contractor, whereby the utilization rate of the apparatusis very high.

The idea of one embodiment is that a large quantity of paste batchesformed by the mixer are unloaded into a uniform hardenable structure. Inother words, by way of unloading, an artificial rock or large hardenablemounds, heaps or clamps will be cast as batch casting. The casting maybe carried out in a mould-free manner over a ground-supported planesurface.

The idea of one embodiment is that the proposed arrangement furthercomprises a quarrying device for quarrying the hardened paste in thecasting area. The material extracted by quarrying, i.e. quarry material,is fed to a crusher device for crushing it into a crushed material. Thecrushed material may be transferred from the crusher by means of aconveyor into heaps in a temporary storage area. Transfer and handlingof the crushed material is easy compared to the handling of rawmaterials and the paste formed from the raw materials. Handling of thecrushed material does not differ from the handling of virgin crushed orangular stone.

The idea of one embodiment is that the geopolymer paste cast onto thecasting site is allowed to harden into an artificial rock, and blocksfitting into a feed opening or mouth of the crusher device are extractedfrom the artificial rock by the quarrying device.

The idea of one embodiment is that after being unloaded, the paste isallowed to harden to a compression strength of at least 1 Mpa beforecrushing. Thereby the quality of the crushed material will be good, andcrushing itself will be carried out smoothly.

The idea of one embodiment is that the factory waste disposal site is inconnection with a pulp mill. The pulp mill produces green liquorprecipitate as a side-stream material which is tipped in a waste pile atthe factory waste disposal site. The first industrial side-streammaterial taken from the waste pile with the mixer is thus green liquorprecipitate, which is also called dregs. Green liquor precipitate is adifficultly handleable material and the solution proposed in thisdocument introduces a simple solution for handling it.

The idea of one embodiment is that the first industrial side-streammaterial taken from the waste pile with the mixer is green liquorprecipitate. Green liquor precipitate, i.e. dregs, is difficultlyhandleable waste. By means of the proposed solution, the dregs areuninterruptedly transported by means of a single transfer means to anunloading point or up to the casting area without intermediate unloadingor loading stages.

The idea of one embodiment is that the first industrial side-streammaterial is the above-mentioned green liquor precipitate. In this casethe second industrial side-stream material fed by a first feed device ofthe admixture station is blast furnace slag or metakaolin. In testsperformed, these side-stream materials were found to suit particularlywell together in the manufacture of a compression-resistant geopolymer.The price of green liquor precipitate is negative, i.e. because of itssafe use, the waste management fees as defined by waste legislation maybe avoided. Further, the price of said blast furnace slag and metakaolinis low as compared to many other side-stream materials. Said materialsand their mixtures contain silicon oxide and aluminium oxide which areneeded in the reaction and hardening of the geopolymer. It may also bepossible to use a material equivalent to said blast furnace slag andmetakaolin in having a similar combination of elements as admixture withthe dregs.

The idea of one embodiment is that the admixture station furthercomprises a third feed device for feeding lye, i.e. sodium hydroxide(NaOH), into the mixer, and further a fourth feed device for feedingwaterglass, i.e. sodium silicate Na₄SiO₄, into the mixer.

The idea of one embodiment is that the hardenable paste mixed in themixer comprises, as the main component, green liquor precipitate andblast furnace slag, metakaolin or the like. In addition, either lye,waterglass or both of them are mixed into the paste as activators. Ahardened material formed from these substances has been found to have aparticularly good compression strength as well as insolubility in tests.

The idea of one embodiment is that the admixture station comprises afifth feed device for feeding water into the mixer in order to adjustthe moisture content of the paste being mixed.

The idea of one embodiment is that the solution relates to a method formixing a paste. In the method, at least two industrial side-streammaterials are mixed together in the manufacture of a geopolymer. Themixing is carried out in a mixer arranged onto a movable work machine.The idea of one embodiment is that the solution relates to a method inwhich the mixer is forced by the work machine into a waste pile forloading a first side-stream material into the mixer. After loading, theloaded portion of the first side-stream material is transferred in themixer from the waste pile to an admixture station. At the admixturestation, at least one second side-stream material is added into thefirst side-stream material located in the mixer. Then the materialslocated in the mixer are mixed by means of rotary mixer elements of themixer. Finally, the mixed paste is transferred in the mixer of the workmachine to a casting area and unloaded.

The idea of one embodiment is that the mixer is unloaded by tilting itsfeed opening in a downward direction and by simultaneously operating themixer elements.

The idea of one embodiment is that a mass of the first side-streammaterial taken by the mixer from the waste pile is weighed. In addition,the amount of materials fed at the admixture station is adjusted inresponse to the determined mass.

The idea of one embodiment is that moisture of the first side-streammaterial taken into the mixer is determined, and water is added to themixer at the admixture station in response to the determined moisturefalling below a determined minimum limit.

The idea of one embodiment is that the solution relates to a method inwhich several batches of a hardenable geopolymer paste are unloaded ontoa casting area from the mixer in order to provide a uniform castingformation. The paste is allowed to dry for at least two days so that thematerial obtains a compression strength which is suitable for crushing.Then, smaller blocks are quarried from the hardened or partly hardenedcasting formation and the blocks are crushed in a crusher device toobtain a fraction which is smaller than a predetermined grain size.

The idea of one embodiment is that the material is allowed to reach itsfinal hardness in the crushed form. Full hardness of the material isgenerally reached within about 90 days, but crushing capacity andnecessary strength for crushing are often reached already within a fewdays from casting. The final hardness is thereby reached at the site ofusage. When quarrying and crushing are carried out for material havingonly reached its partial hardness, the work is quicker to carry out anddoes not require so heavy equipment as would be needed for breaking afully hardened material. In addition, the solution is ecological,because quarrying and crushing require less energy when the material hasnot yet reached the full strength.

The idea of one embodiment is that the paste is foamed after mixing theadmixtures. By means of foaming a lightweight yet strong material isproducible. This type of foamed crushed material with a porous structuremay have a good thermal insulation capacity, whereby it may also be usedas frost insulation.

The idea of one embodiment is that the foaming may be carried outchemically for example by adding hydrogen peroxide to the paste, oralternatively mechanically by using a foaming apparatus which maysubstantially correspond to an apparatus designed for foaming concrete.

The idea of one embodiment is that only one side-stream material ismixed by the mixer with the other components to form a geopolymer.

The idea of one embodiment is that three side-stream materials are mixedby the mixer with other the components to form a geopolymer.

The above-described embodiments and their features may be combined witheach other to provide desired configurations.

SHORT DESCRIPTION OF THE FIGURES

Some embodiments of the proposed solution are illustrated in more detailin the following figures, in which

FIG. 1 is a schematic and simplified diagram presenting admixtures ofone geopolymer,

FIG. 2 is a schematic and simplified diagram presenting the manufactureof one geopolymeric earthwork material,

FIG. 3 schematically illustrates the manufacture of one geopolymer at afactory waste disposal site,

FIG. 4 schematically illustrates one mixing unit formed by a mixer and awork machine,

FIG. 5 schematically illustrates the use of one mixer in differentstages of a geopolymer manufacturing process,

FIG. 6 illustrates one mixer and its rotary mixer shaft as seen from thefront,

FIG. 7 schematically illustrates one mixer and its apparatuses as seenfrom the side; and

FIG. 8 is a schematic diagram presenting components of a mixed paste.

For clarity purposes, some embodiments of the proposed solutions areillustrated in the figures in a simplified form. In the figures, samereference numerals are used to denote the same elements and features.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

FIG. 1 represents a geopolymer comprising at least two side-streammaterials. In some cases even more side-stream materials may be used inthe formation of a hardenable paste. A common feature of theseside-stream materials and their mixture is that they comprise siliconoxide SiO₂ and aluminium oxide Al₂O₃ which react with each other andform a paste which hardens to a compression-resistant state. Thecompression strength achieved is at least 10 Mpa, but is generally over40 Mpa, and sometimes even over 80 Mpa.

Industrial side-stream materials are e.g. tailings, such as red mud.Further side-stream materials are slags from the steel industry, such asblast furnace slag, steel slag and refined steel slag. Ashes from theenergy industry, such as organic ashes produced in the combustion ofwood as well as inorganic ashes produced in the combustion of coal, oilshale and the like are also side-stream materials. The ashes may includefly ash, grate ash or bottom ash formed in boilers. Further side-streammaterials are produced in the forest industry. In the pulp industry,green liquor precipitate is formed as waste in large quantities.

Green liquor precipitate is a side-stream material formed in the woodprocessing industry in the manufacture of pulp, and is also calleddregs. Dregs are produced in a sulphate process at a chemical recoveryline. The dregs are removed from green liquor in a green liquorclarifier before conducting green liquor to causticizing, i.e. to themanufacture of cooking chemicals. Green liquor precipitate is a mixtureof various green liquor insoluble substances, inorganic salts, such asoxides, carbonates and sulphides. It also contains hazardous metals inaddition to the normal alkali metals and calcium and magnesium. Dregsremoved from the process are washed in order to recover the sodiumcompounds contained in them. The washed dregs are dried before tippingin a waste disposal site, and their typical dry matter content is about50%.

Further, one or more activators may be added to the mixture formed bythe side-stream materials, or in some cases the activator is not neededbut the side-stream materials react with each other. Or, they may reactafter water has been added to the mixture.

The method and solution proposed in this document may be used in aversatile way for the manufacture of products comprising variousindustrial side-stream materials.

Further, it is stated that in some cases only one side-stream materialmay be used in the manufacture of a geopolymer. In that case, otheradmixtures are mixed with the side-stream material in a mixer.

FIG. 2 is a diagram presenting an earthwork material manufacturingprocess as described in this application. The steps and featurespresented in the diagram have been described in detail alreadyhereinabove, and are also disclosed in the description of FIG. 3.

In FIG. 3 an industrial plant or a factory 1 produces a firstside-stream material 2 which is tipped in a waste pile 4 at a factorywaste disposal site 3. The waste pile 4 may be a mound-like formation, aheap or a clamp. It may also be a previously deposited formation.

A work machine 5 has a mixer 6 by which the side-stream material 2 istaken from the waste pile 4. A mass of the loaded material and possiblyother properties may be measured and the measurement results are sent toa control unit CU of an admixture station 7. The combination of the workmachine 5 and the mixer 6, i.e. a mixing unit 8, transfers to theadmixture station 7 where a second side-stream material may be fed intothe mixer 6 from a second feed device 9. Activators may be fed from athird feed device 10 and a fourth feed device 11. Further, water may befed from a fifth feed device 12 if necessary. The feed devices 9-12 maycomprise upper containers or hoppers below which the mixer 6 may bepositioned for admixing. In some cases the second side-stream materialis not fed into the paste.

The materials fed into the mixer 6 are mixed during their transfer, andfinally the formed paste is unloaded onto a casting area 13. A uniformlarger formation may be formed from the paste, for example a type ofartificial rock 14. The material is allowed to harden at least to apartial hardness. Blocks 16 may be quarried from the artificial rock 14for example with a hydraulic impact hammer 15 as small-batch quarrying,with wedges or some other quarrying method. When quarrying is carriedout before reaching the final hardness, it may be performed even with abucket of an excavator or a rock tine mounted to it. The extractedblocks 16 may be fed into a feed opening of a crusher device 17 andcrushed into crushed material 18 of a desired grain size. The crushedmaterial 18 may be stored temporarily 19 and transferred to a site ofusage by road transport.

The crusher device 17 may be for example a jaw crusher, an impactcrusher or a cone crusher.

If necessary, the quarrying and crushing may also be performed after alonger time, whereby the quarrying and crushing equipment is selectedaccording to the situation.

FIG. 4 illustrates a situation where the work machine 5 pushes the mixer6 into the waste pile 4 and thereby loads the first side-stream material2. In FIG. 4 it is shown that the mixer 6 may comprise two horizontalmixer shafts 20 a, 20 b which are provided with mixer elements and whichmay be rotated.

In FIG. 5 it is shown that the mixer 5 may be tilted to a desiredposition about a pivot joint 21 and introduced at the admixture station7 under the feed device 9 for feeding the admixtures. The top of themixer 5 is open, for receiving the admixtures. Further, the mixer 5 maybe kept in a desired tilt position during the mixing. The mixing may becarried out by the rotary mixer shafts 20 a, 20 b during the transfer.When the paste has been mixed, it may be foamed before unloading, ifdesired. Foaming devices may be arranged in connection with the mixer 5.At the unloading site the mixer 5 may be tilted in a downward directionabout the pivot joint 21, and the unloading may further be facilitatedby means of the mixer devices.

The unloading may be carried out by way of batch casting into a castingpile. In this process a large quantity of smaller batches 22 form alarger formation.

In FIG. 6 it is illustrated that the rotary mixer shaft 20 of the mixer5 may comprise a large number or arms 23 which are provided with mixingsurfaces 24. In a mixer device 26 there may be one, two or even more ofsuch parallel mixer shafts 20 provided with mixer blades 28.Alternatively the mixer shafts may comprise screw-type mixing surfaces.

In FIG. 7 it is illustrated that the mixer shafts 20 a, 20 b of themixer device 26 of the mixer 5 may rotate in opposite directions. Arotation motor M for rotating the shafts 20 is located outside thebucket part 27. Further, the mixer 5 comprises a connecting device 25for connecting it to the work machine. The mixer 5 may also be providedwith a sensor S1 for determining a mass of the material located in themixer, as well as with a sensor S2 for determining moisture or otherproperty of the material. A vibrator T may also be arranged with themixer to provide vibration facilitating the unloading and mixing.

FIG. 7 additionally illustrates a sensor S3 or a corresponding measuringdevice by which a resistance to rotation caused by the paste being mixedmay be determined by monitoring the motor M. The resistance to rotationmay manifest as an increased need for rotation torque, rotating force,drive energy or the like, or alternatively for example from a change inthe rotation speed. The resistance to rotation may provide informationon the plasticity and also moisture of the paste. Further, there may beone or more cameras K in connection with the mixer to produce visualdata which may be transmitted to an operator for making sensoryobservations on the paste being mixed. A skilled operator may see theplasticity of the paste from a video camera picture.

FIG. 8 presents possible components of a geopolymer comprising aside-stream material from the pulp industry.

The figures and their description are only intended to illustrate theinventive idea. However, the scope of protection of the invention isdefined in the claims of the application.

1. A mixer for mixing an industrial side-stream material in themanufacture of a geopolymer, characterized in that the mixer comprises:a bucket part for loading and transferring the side-stream material; amixer apparatus for mixing the side-stream material which has beenloaded into the space delimited by the bucket part; a connecting devicefor connecting the mixer to a boom of a work machine; and at least onemeasuring device for determining properties of the material in themixer.
 2. The mixer according to claim 1, characterized in that thebucket part of the mixer is an open-top structure, whereby the mixer isarranged to receive material from an upper feed station.
 3. The mixeraccording to claim 1, wherein the mixer is tiltable from a mixingposition to an unloading position, in which unloading position thematerial located in the mixer is arranged to flow out from the bucketpart by the effect of gravity.
 4. The mixer according to claim 1,wherein the mixer apparatus of the mixer is operatable during theunloading.
 5. The mixer according to claim 1, wherein the mixercomprises at least one vibrator device facilitating the unloading of thebucket part.
 6. The mixer according to claim 1, wherein the mixercomprises at least one horizontal mixer shaft which is rotatable bymeans of a rotation motor about its longitudinal axis; and the mixershaft is provided with a plurality of mixer blades having mixingsurfaces in an angular position relative to the longitudinal directionof the mixer shaft.
 7. The mixer according to claim 1, wherein the mixercomprises two horizontal mixer shafts which are rotatable by means of atleast one rotation motor about their longitudinal axes; the rotationdirections of the mixer shafts are opposite to each other; each one ofthe mixer shafts is provided with a plurality of mixer blades havingmixing surfaces in an angular position relative to the longitudinaldirection of the mixer shaft; and the mixer blades of the adjacent mixershafts are provided at axially different locations relative to eachother, such that the mixer blades of the adjacent mixer shafts arepartly overlapped.
 8. A mixing unit, for mixing an industrialside-stream material in the manufacture of a geopolymer, characterizedin that the mixing unit comprises: a movable work machine provided witha boom; a mixer connected to said boom, and which mixer is as definedaccording to claim 1.